Peripheral nervous system manifestations of Sjögren syndrome: clinical patterns, diagnostic paradigms, etiopathogenesis, and therapeutic strategies.

Abstract Sjogren syndrome is among the most common autoimmune diseases affecting adults in the United States, and is frequently regarded as an immune-mediated exocrinopathy exclusively causing dry eyes and dry mouth. However, as a systemic rheumatic disease, there can be various "extraglandular" complications. The eclectic permutation of peripheral nervous system (PNS) syndromes which occur in Sjogren patients are among the most common and severe extraglandular complications. This review article highlights the evaluation, differential diagnosis, immunopathogenic mechanisms, and potential treatment options of these PNS complications encountered by neurologists. The sensory neuropathies constitute the most frequent PNS complication. Sjogren patients can suffer from severe neuropathic pain, with small-fiber neuropathy causing lancinating or burning pain which can disproportionately affect the proximal torso or extremities, and the face (ie, in a "non-length-dependent distribution"). The technique of skin biopsy, assessing for the intraepidermal nerve fiber density of unmyelinated nerves, provides a useful technique for neurologists to diagnose small-fiber neuropathies, especially when there is such a non-length-dependent distribution. Other diagnostic techniques (ie, electromyography/nerve-conduction studies, evoked potentials, nerve and muscle biopsy) may be useful in specific subtypes of neuropathies. A rational approach to treatment requires a careful appraisal of the clinical subtype of the neuropathy, as well as a familiarity with such discriminating immunopathogenic mechanisms. The application of the traditional armamentarium used for neuropathic pain can be especially challenging. Sjogren patients can suffer from debilitating fatigue, sicca symptoms, and autonomic findings; as such manifestations can be complications of various neuropathic agents, neurologists should understand how to minimize such iatrogenic complications. Therefore, this article will empower neurologists to more effectively collaborate with rheumatologists, in the diagnosis and treatment of Sjogren patients with PNS complications.